How to save a render image as JPEG with white background instead of default black background at alpha transparent areas?
No, but it's quite simple to do with nodes..

In the compositor (press &#9096; Ctrl&#8592; Left arrow), enable Use Nodes in the header and add an alpha over node (&#8679; ShiftA> Color):



The color in the top slot is the color which will be used instead of transparency.

Now transparency will be automatically filled in with white (or whatever is in the top socket) when the scene is rendered.